1. Field of the Invention
This invention relates to light emitting devices, and in particular relates to light diffusion elements thereof.
2. Description of the Related Art
Present lighting fixtures have higher brightness than previous ones due to the development of technology and improvement of lighting devices thereof. For example, light emitting diodes (LED) which have long lifetimes, low power consumption, and high brightness are widely applied in light fixtures everywhere.
Although lighting fixtures with high brightness may efficiently enhance brightness of the surrounding, their focused brightness is harsh to users. In the worst case, the eyes of a user could be damaged by the focused brightness. In addition, lighting devices emit radiative light rather than evenly distributed light.
To solve the focused brightness problem of LEDs, light diffusion element can be set outside of the light source. The light diffusion element can be mainly manufactured by two methods. The first method is to add inorganic particles (such as silicon oxide, titanium oxide, or the likes) to polymers with high transparency (such as polycarbonate, poly methylmethacrylate, polystyrene, or the likes). The optical properties of the composite materials are determined by factors such as the size and amount of inorganic particles. Unfortunately, it is difficult to evenly disperse the inorganic particles in the organic polymer, and therefore the surface of the inorganic particles must be modified. The second method is to create wave- or lens-shaped micro structures on the surface of a polymer that has high transparency. These two methods, however, increase the complication and cost of mass production processes.
Accordingly, a novel material composition to solve the problems of the conventional light diffusion element is called for.